Hot Water Heater Backdrafting

A water heater backdrafts when the exhaust gases from an atmospherically vented water heater spill out into the room rather than safely leaving the house through the vent.

Hot water heater backdrafting.

If a water heater backdrafts it means that potentially hazardous exhaust gases are coming back into the home. Some water heaters will be right on the brink of backdrafting even with a proper installation and all it takes is a single bathroom exhaust fan to pull enough air out of the house to make the water heater backdraft. When homeowners replace older furnaces with more efficient models that don t use the chimney to vent gas water heaters are often left as the only device venting into the chimney which is now oversized for the water heater alone. For a water heater to draft properly it needs to have plenty of available air.

This problem affects mainly the atmospheric gas type water heaters that use the natural convection for the removal of the products of combustion known as the exhaust gases. Fuel fired water heaters boilers wall heaters and furnaces are designed to exhaust the by products of combustion to the outdoors through a flue. Backdrafting can have many causes but it is most commonly due to poor vent design or installation and or an imbalance of air volume in the home. These heating devices are identified by the presence of a draft hood also called a draft diverter.

Exhaust gases contain carbon monoxide and high levels of moisture so this is always a condition that should be corrected. The most common problem associated with water heater venting is a condition called backdrafting in which exhaust gases from the water heater fail to exit the home via the vent and instead end up in the house. Causes and recognition backdrafting is a potentially fatal health hazard connected with the presence of heating appliances that use atmospheric draft to exhaust toxic combustion gasses to the home exterior. The simplest way to prevent backdrafting is to provide a source of replacement air also called combustion air for your furnace water heater and fireplace to replace the air that flows up the chimney with the exhaust fumes fig.

A common source of backdrafting is orphaned water heaters. Another way dangerous backdrafting can occur is through improperly configured flues or flue blockages warns gromicko. The main reasons for the backdrafting at the water heater are the poor vent installation and the obstructions found in the vent pipe.